Distributed cache—adaptive multicast architecture for bandwidth reduction

ABSTRACT

Disclosed is a method and system for maximizing the use of available bandwidth on an ISP communication system between an Internet Service Provider (ISP) and remote locations where at least one of the remote locations has a remote cache. An embodiment may create a pool of the cacheable objects being sent to the remote locations from the downstream traffic. An embodiment may determine bandwidth savings for each object in the pool of cacheable objects that would be achieved by remotely caching each object and prioritize the pool of cacheable objects based on the determined bandwidth savings for each object. An embodiment may create a queue of objects to multicast to the remote caches based on the pool of cacheable objects and the remaining multicast bandwidth and then multicast the queue to the remote caches. The remote caches may intercept and reply to requests for objects held in the remote cache without accessing the ISP communication system, thus, saving bandwidth on the ISP communication system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. non-provisional applicationSer. No. 12/554,585, filed Sep. 4, 2009, entitled “DistributedCache—Adaptive Multicast Architecture for Bandwidth Reduction,” all ofwhich is specifically incorporated herein by reference for all that itdiscloses and teaches.

BACKGROUND OF THE INVENTION

Internet Service Providers (ISPs) provide access to the Internet forclients of the ISPs. Direct access by each Internet user to the Internetbackbone is not typically implemented as a direct connection to theInternet backbone because such a direct connection is expensive and isgenerally limited in geographical availability. Also, controlling thenumber and ownership of direct connections to the Internet backbone isused by ISPs to discourage security threats to the Internet.

With respect to connections between the ISP and the ISP clients,typically, an ISP provides a private/proprietary communication system toconnect ISP clients to the ISP. Further, the ISP maintains one or moredirect connections to the public Internet and provides the bridgeconnection between the public Internet and the private/proprietarycommunication system connecting the ISP to the ISP clients. The directconnections to the Internet are implemented, many times, via a wiredsystem with sufficient bandwidth that the aggregate data usage of theISP clients is not limited by the ISP connections to the Internet.However, the bandwidth of the communication system connecting the ISP tothe clients has generally been bandwidth limited.

In the early days of Internet use, a typical communication systemconnecting the ISP to the ISP clients used phone modems that,eventually, operated up to 56 kbps (kilo bits per second). As thepopularity of the Internet increased, a desire for faster clientconnections also increased. Thus, many ISPs began to provide “broadband”access in the 256 kbps to 1 Mbps (mega bits per second), or greater,speed ranges between the ISP and the ISP client. With time, theavailable “broadband” speeds increased to a typical current speed of 5-6Mbps with speeds of 20 Mbps or higher available from some ISPs. Some ofthe typical “broadband” communication systems include: satellite basedcommunications, cable modem based communications (i.e., based on thecable television connections already in place), and Digital SubscriberLine (DSL) technology.

While “broadband” connections made ISP client access to the Internetsignificantly faster than the prior phone modem technology, thecommunication system connection between the ISP and the ISP client stillremained a significant bottleneck in the potential speed of access forISP clients. Depending on the technology, the bandwidth (effective sizeof the communication pipe between the ISP and the ISP client) was sharedbetween multiple clients and the usage of one client could adverselyaffect other clients. For other “broadband” technologies, thecommunication speed in “bits per second” was relatively fast, but due tothe connection medium and signal travel distance, a significant amountof the response time between requesting a web page and receiving the webpage at the ISP client location was due to the time latency needed forthe signal to travel the full signal travel distance to and from the ISPand not as much for the actual communication speed in “bits per second.”

SUMMARY OF THE INVENTION

An embodiment of the present invention may comprise a computerizedmethod for maximizing use of communication bandwidth on an ISPcommunication system connecting at least one remote location to anInternet Service Provider (ISP), the ISP communication system having amaximum total downstream bandwidth available to transmit objectsdownstream from the ISP to the at least one remote location, the atleast one remote location having a remote cache, the computerized methodcomprising: determining a bandwidth savings from remote caching for eachrequested object in a pool of cacheable objects as a function of adelivery cost/size of each requested object, a Time To Live (TTL)/expirytime of each requested object, and a frequency of request for eachrequested object, the pool of cacheable objects being requested objectscontained in downstream unicast replies of downstream unicastcommunication traffic of the ISP communication system; prioritizing therequested objects in the pool of cacheable objects based on thedetermined bandwidth savings for each requested object in the pool ofcacheable objects; determining a sub-group of the requested objects inthe pool of cacheable objects to place in a queue of multicast cacheableobjects to multicast to the remote cache at the at least one remotelocation based on the prioritized pool of cacheable objects and anavailable downstream multicast bandwidth; delivering objects in thequeue of multicast cacheable objects to the remote cache at the at leastone remote location via multicast transmissions downstream from the ISPto the remote location; intercepting requests sent upstream from the atleast one remote location for objects contained in the remote cache atthe remote cache; and responding to the intercepted requests by theremote cache at the at least one remote location with replies containingthe requested objects contained in the remote cache such that upstreamand downstream bandwidth on the ISP communication system is saved byexcluding upstream requests for, and downstream replies containing, therequested objects contained in the remote cache.

An embodiment of the present invention may further comprise adistributed cache adaptive multicast system for maximizing use ofcommunication bandwidth on an ISP communication system connecting atleast one remote location to an Internet Service Provider (ISP), the ISPcommunication system having a maximum total downstream bandwidthavailable to transmit objects downstream from the ISP to the at leastone remote location, the at least one remote location having a remotecache, the distributed cache adaptive multicast system comprising: aprioritizer subsystem that determines a bandwidth savings from remotecaching for each requested object in the pool of cacheable objects as afunction of a delivery cost/size of each requested object, a Time ToLive (TTL)/expiry time of each requested object, and a frequency ofrequest for each requested object, the pool of cacheable objects beingrequested objects contained in downstream unicast replies of downstreamunicast communication traffic of the ISP communication system, and thatprioritizes the requested objects in the pool of cacheable objects basedon the determined bandwidth savings for each requested object in thepool of cacheable objects; a multicast queue subsystem that determines asub-group of the requested objects in the pool of cacheable objects toplace in a queue of multicast cacheable objects to multicast to theremote cache at the at least one remote location based on theprioritized pool of cacheable objects and the available downstreammulticast bandwidth; and a multicast delivery subsystem that deliversobjects in the queue of multicast cacheable objects to the remote cacheat the at least one remote location via multicast transmissionsdownstream from the ISP to the remote location in order to permit the atleast one remote cache to intercept requests sent upstream from the atleast one remote location for objects contained in the remote cache atthe remote cache, and to respond to the intercepted requests by theremote cache at the at least one remote location with replies containingthe requested objects contained in the remote cache such that upstreamand downstream bandwidth on the ISP communication system is saved byexcluding upstream requests for and downstream replies containing therequested objects contained in the remote cache.

An embodiment of the present invention may further comprise adistributed cache adaptive multicast system for maximizing use ofcommunication bandwidth on an ISP communication system connecting atleast one remote location to an Internet Service Provider (ISP), the ISPcommunication system having a maximum total downstream bandwidthavailable to transmit objects downstream from the ISP to the at leastone remote location, the at least one remote location having a remotecache, the distributed cache adaptive multicast system comprising: meansfor determining a bandwidth savings from remote caching for eachrequested object in the pool of cacheable objects as a function of adelivery cost/size of each requested object, a Time To Live (TTL)/expirytime of each requested object, and a frequency of request for eachrequested object, the pool of cacheable objects being requested objectscontained in downstream unicast replies of downstream unicastcommunication traffic of the ISP communication system; means forprioritizing the requested objects in the pool of cacheable objectsbased on the determined bandwidth savings for each requested object inthe pool of cacheable objects; means for determining a sub-group of therequested objects in the pool of cacheable objects to place in a queueof multicast cacheable objects to multicast to the remote cache at theat least one remote location based on the prioritized pool of cacheableobjects and the available downstream multicast bandwidth; means fordelivering objects in the queue of multicast cacheable objects to theremote cache at the at least one remote location via multicasttransmissions downstream from the ISP to the remote location; means forintercepting requests sent upstream from the at least one remotelocation for objects contained in the remote cache at the remote cache;and means for responding to the intercepted requests by the remote cacheat the at least one remote location with replies containing therequested objects contained in the remote cache such that upstream anddownstream bandwidth on the ISP communication system is saved byexcluding upstream requests for, and downstream replies containing, therequested objects contained in the remote cache.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings,

FIG. 1 is a schematic illustration of the general Internet connectionarchitecture for connecting an Internet Service Provider (ISP) to aremote location having a remote cache.

FIG. 2 is a schematic illustration of a satellite based ISP Internetconnection architecture used to connect an ISP to a remote locationhaving a remote cache.

FIG. 3 is a top-level schematic illustration of ISP communications usinga distributed cache—adaptive multicast architecture.

FIG. 4 is detailed flow chart/schematic illustration of the operation ofthe harvester in a distributed cache—adaptive multicast architecture.

FIG. 5 is a flow chart describing the operation of an embodiment thatmaximizes use of available bandwidth on an ISP to ISP subscriber/clientcommunication system.

FIG. 6 is a flow chart describing operation of the prioritizer toprioritize objects in the pool of cacheable objects.

FIG. 7 is a flow chart describing operation of an embodiment tooverwrite or create Time To Live (TTL)/expiry times for objects in themulticast queue.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 is a schematic illustration 100 of the general Internetconnection architecture for connecting an Internet Service Provider(ISP) 104 to a remote location 108 having a remote cache 110. One ormore Internet end user devices 112 may connect to the Internet 102through an ISP 104. The Internet 102 is connected to the ISP 104 andconnects to the remote location(s) 114 via the ISP communication system106. The ISP communication system 106 may be limited in how much datamay be delivered (typically measured in bits per second—bps). Theschematic illustration 100 shown in FIG. 1 illustrates a single remotelocation 114, but various embodiments may have the ISP 104 concurrentlyconnect to one more remote locations 114 via the ISP communicationsystem 106. In other words, the ISP 104 connects to at least one remotelocation 114 via the ISP communication system 106. The ISP 104 operatesas a communication bridge between the communication protocol used on theISP communication system 106 and the communication protocol used toconnect to the Internet 102. Accordingly, the equipment at the ISP 104may include one or more computing devices capable of performing thecommunication bridge function, including both dedicated computingequipment as well as a general purpose computer containing computerinstructions to perform the appropriate functions required of the ISP104. The one or more computing devices making up the computer systemperforming the functions of the ISP 104 may include at least onecomputer readable storage medium that stores the necessary computerinstructions to perform the operations of the ISP 104.

The remote location 114 may include a remote modem (transceiver) 108, aremote cache 110, and one or more end user devices 112 that access theInternet 102 through the ISP 104. One skilled in the art will recognizethat the functions performed by the remote modem/transceiver 108, theremote cache 110 and/or the end user devices 112 may be combinedtogether into a single device and/or two devices rather than threeseparate devices. One skilled in the art will also recognize that theremote cache 110 may be located before or after the remotemodem/transceiver 108. The remote cache 110 as shown in FIG. 1 islocated after the remote modem/transceiver 108 as it is anticipated thatthe cost for communication parts/devices operating on the networkingprotocols expected at the remote location (e.g., standard Ethernet) isless expensive and cumbersome to work with than for the communicationparts/equipment designed to communicate on the ISP communication system106 (e.g., satellite, cable, or Digital Subscriber Line—DSL), but thismay not necessarily be true for all embodiments. Further, if the remotecache 110 and the remote modem/transceiver 108 are combined into asingle device, it may make little difference in operation and/orpart/equipment cost of the single device to place the remote cache 110prior to the remote modem/transceiver 108 that converts the signal fromthe ISP communication system 106 into a signal commonly used fornetworking at an ISP client/remote location 114. Similar to theequipment utilized at the ISP 104, the equipment at the remote location114 may include one or more computing devices to perform the functionsof the remote modem/transceiver 108, the remote cache 110, and/or theend user devices 112. Computing devices capable of performing theappropriate functions at the remote location include both dedicatedcomputing equipment as well as a general purpose computer containingcomputer instructions to perform the necessary operations at the remotelocation 114. The one or more computing devices making up the computersystem performing the functions at the remote location 114 may includeat least one computer readable storage medium that stores the necessarycomputer instructions to perform the operations of an embodiment at theremote location 114.

In the Internet connection architecture 100 shown in FIG. 1, the typicalISP communication system connection 106 is augmented by the addition ofa remote cache 110 located at the remote location 114 of a user. Theremote cache 110 stores/caches Internet objects (i.e., Internet dataobjects, data, items, etc.) at the remote location 114 so that the enduser devices 112 at the remote location 114 may repeatedly request,receive, and utilize the objects stored in the remote cache 110 withoutthe need to request or receive a reply from the Internet over the ISPcommunication system for each instance of a request by the end userdevices 112 for a remotely cached object requested. As the remote cache110 stores information, the one or more computing devices performing thefunctions of the remote cache 110 may necessarily include at least onecomputer readable storage medium to store the cached Internet objects.Various embodiments may utilize commercially available software toperform the functions of the remote cache 110 such as web or Hyper TextTransfer Protocol (HTTP) server software. For instance, an embodimentmay utilize the open source Apache server software to perform thecaching functions of the remote cache 110. Other embodiments may utilizethe Internet Information Servers (IIS) web/HTTP software available fromMicrosoft Corporation or some other web/HTTP server software.Embodiments may combine the use of various web/HTTP server softwareapplications such as Apache and IIS as desired by the system designer.Various embodiments may further connect at least one remote locationthat does not have/utilize a remote cache to the same ISP communicationsystem 106 connecting to the one or more remote locations 114 havingremote caches 110.

In operation, the end user devices 112 deliver all Internetdata/information requests 122 upstream to the remote cache 110. Theremote cache inspects all the upstream requests 122 from the end userdevices 112 and returns downstream replies 120 with any informationstored in the remote cache 120 without forwarding the request for theinformation to the ISP 104 over the ISP communication system 106.Upstream requests 122 from the end user devices 112 that requestinformation found in the remote cache 110 may be referred to as upstream“hit” requests. Upstream requests 122 from the end user devices 112 thatrequest information not found in the remote cache 110 may be referred toas upstream “miss” requests. Any of the upstream requests 122 from theend user devices 112 that “miss” and do not locate information in theremote cache 110 are sent as upstream requests 124 to the Internet 102via the remote modem/transceiver 108, the ISP communication system 106and the ISP 104. Necessarily, the upstream requests 124 for data“missed” in the remote cache 110 utilize the ISP communication systembandwidth 106 to communicate the information. After receiving theupstream requests 124 for the data missed by the remote cache 110, theInternet sends replies downstream 116 that will eventually be receivedby the requesting end user devices 112 at the remote location 114. Thedownstream replies 116 for the information missed at the remote cache110 is delivered to the ISP 104. The ISP 104 then passes the downstreamreplies for the misses 116, 118 over the ISP communication system 106 tothe remote location 114. The downstream “miss” replies 116 are typicallyunicast messages directed to each individual end user device/application112 that has requested an object. Thus multiple end userdevices/applications 112 at either a single or multiple remote locations114 may request the same data object, but necessitate a separate unicastreply to be directed to each end user device/application 112. A unicastmessage is a message intended for and delivered to a single requestingapplication/device. The ISP 104 may also send multicast messages 118including information that is to be stored by the remote cache 110 tothe remote cache 110 concurrently with the downstream miss replies 116.By utilizing multicast technology, a single message may be transmittedto multiple remote caches 110 at multiple remote locations 114instructing the remote caches 110 to store the attached multicast data118. Thus, downstream bandwidth on the ISP communication system 106 usedfor delivering information to multiple remote caches 110 is minimized bythe use of the multicast technology. Future requests for the sameobjects by other remote locations 114 may then also be responded to bythe remote cache 110 for each remote additional remote location 114,also saving ISP communication system 106 bandwidth to permit moreefficient bandwidth use by maximizing the ISP communication system 106bandwidth. The remote cache 110 receives the downstream unicast missreplies combined with the multicast cache data 118 sent by the ISP 104.The remote cache 110 removes the multicast cache data from thedownstream unicast miss replies and multicast data stream 118 and storesthe associated data in the remote cache 110. The remote cache 110 thenpasses on the downstream unicast miss replies 116 along with replies fordata objects found (i.e., “hit”) in the remote cache 110 such that thedownstream signal after the remote cache 110 includes all downstreamreplies 120 to all upstream requests from the end user devices 112.

The remote cache 110 effectively removes the need to send requests andreceive replies for data stored in the remote cache 110 over the ISPcommunication system and/or the Internet. The more remote locations thatimplement a remote cache, the more requests and replies are not sentover the ISP communication system 106 and/or the Internet 102. Thus, theISP communication system bandwidth usage is reduced (i.e., saved) andthe system may operate more quickly/efficiently and/or may handle moretraffic, at least from the perspective of the end user devices 112.While the typical limiting transmission system in the Internetconnection for the end user devices 112 is the ISP communication system106, the bandwidth savings from the use of the remote cache 110 alsosaves the same bandwidth on the connection between the ISP 104 and theInternet 102.

FIG. 2 is a schematic illustration 200 of a satellite based ISP Internetconnection architecture used to connect an ISP 206 to a remote location214 having a remote cache 210. The embodiment illustrated 200 in FIG. 2is a particular embodiment of the more general embodiment as disclosedwith respect to and as illustrated 100 in FIG. 1 using satellitecommunication 206 as the ISP communication system 106. As with thegeneral architecture described in the disclosure with respect to FIG. 1,the schematic illustration 200 in FIG. 2 shows a single remote locationfor simplicity when the architecture is capable of supporting one ormany remote locations 214. The ISP 204 connects to the one or moreremote locations 214 via the satellite communication system 206. Eachremote location 214 connects to the satellite communication system 206via a remote modem/transceiver 208, which is connected to the remotecache 210. The end user devices 212 may then be connected to the remotecache 210. As discussed in the disclosure with respect to FIG. 1, theremote cache 210 may be located either before or after the remotemodem/transceiver 208 and/or the remote cache 210 may be combined intoeither the end user device 212 or the remote transceiver 208, both (208,212) of which may also be combined into a single device, as desired bythe system designer.

The remote cache 210 receives all upstream Internet data requests 222.The remote cache 210 replies to the end user devices 212 with data itemsrequested in the upstream requests 222 that are included in the remotecache 210 as part of the data stream of all downstream replies 220 toend user device 212 upstream requests 222. If a data item requested 222by the end user devices 212 is not found (i.e., missed) in the remotecache 210, the upstream requests for the misses 224 is sent to theremote modem/transceiver 208, where the upstream request misses 224 aretransmitted via the satellite communication system 206 to the ISP 204and eventually to the Internet 202. The Internet 202 replies to theupstream request misses 224 with downstream replies for the misses 216containing the requested data objects for the upstream request misses224. The ISP may then add multicast cache data to the downstream replymisses 216 and send the combined downstream reply misses and multicastcache data 218 to the one or more remote locations 214 via the satellitecommunication system 206. The remote cache 210 at each remote location214 may then remove the multicast cache data 218 and store the multicastcache data in the remote cache 210. The downstream reply misses 216 maythen be combined with the replies from the remote cache 210 for therequested data hits found in the remote cache such that the end userdevices receive all downstream replies 220 to all upstream requests 222,including the replies from the remote cache 210 for data found in theremote cache 210 where the upstream request was not sent to the Internet202, the ISP 204, or the satellite communication system 206.

As was described for the system disclosed with respect to FIG. 1, thebandwidth necessary to transmit upstream requests for and downstreamreplies containing data objects found in the remote cache 210 is savedwhen the remote cache 210 replies to a request rather than requiringtransmission to and from the Internet 202 via the ISP 204. In additionto concerns with the “bits per second” bandwidth utilized to handleInternet data request and replies, a satellite communication system 206also has a substantive transmission latency effect 226. Transmission ofa signal up to and down from the satellite 206 over the transmissionsignal path 228 may take a half a second to a second or more. Thus, itmay take one or more seconds (i.e., transmission latency 226) for anupstream request 224 to travel the length of the transmission signalpath 228, regardless of the “bits per second” speed of the satellitecommunication system 206. Hence, even with significant “bits per second”speed, a satellite system may display transmission latency 226 thatmakes system response at the end user device 212 appear to be slowerthan the “bits per second” speed that the satellite communication system206 may otherwise indicate to an end user. The slowing of the end userdevice 212 response times may further be exaggerated if a web pagerequires several upstream request/downstream reply cycles before a webpage is shown. For instance, if a web page includes javascript code thathas to be requested and downloaded and then the downloaded javascriptcode is processed and the javascript processing makes another requestfor an object, then there are two request cycles to effectively displayone object. Another example of multiple requests needed to display asingle object may occur if a web page requires the end user device toidentify the web browser used before sending the web page, the latencyfor the upstream data identifying the web browser will be combined withthe latency of actually delivering the data to the end user devices 212such that the transmission latency 226 observed to receive the data forthe requested web page is effectively doubled. For many web pages theremay be several of request/response cycles before the web page isrendered on the end user device 212, effectively multiplying thetransmission latency time. In addition to the bandwidth savingsdiscussed above, the use of the remote cache 210 for a satellitecommunication system 206 has the additional benefit of eliminating thetransmission latency 226 for each “hit” on requested data 222 found inthe remote cache 210.

FIG. 3 is a top-level schematic illustration 300 of ISP communicationsusing a distributed cache—adaptive multicast architecture. The remotelocations 310 have remote caches 332, 334, and 336. As disclosed withrespect to FIGS. 1 and 2, the remote cache 332 receives all Internetrequests 318 for the location where the remote cache 332 is located. Thefirst remote cache shown 332 replies for all hits 320 found in theremote cache without forwarding the requests for hits upstream to theInternet 302. Any requests that are misses in the remote cache 332(i.e., data is not found in the remote cache 332) are sent to theInternet as upstream request misses 330. The second cache 334 andsubsequent N caches 336 similarly receive all requests 322, 326 from theapplicable remote location 310, respectively, and reply to any hits 324,328, respectively, found in the applicable remote cache 334, 336. Thesecond cache 334 and subsequent N caches 336 also similarly send anyrequests that are misses in the applicable remote cache 334, 336 (i.e.,data is not found in the remote cache 334 or 336, respectively) to theInternet as upstream request misses 330. The Internet 302 handles theupstream request misses 330 and sends unicast replies to the missesdownstream 314 to all subscribers/ISP clients 312 via the ISPcommunication system 308 where each unicast reply 314 is specificallyaddressed to a particular end user device/application. As disclosed withrespect to FIGS. 1 and/or 2, when the remote caches 332, 334, 336intercept and reply to requests 318, 322, 326 without the need torequest information from the Internet, overall bandwidth of the ISPcommunication system is saved and/or the transmission latency effectexperienced by users may be significantly reduced (e.g., transmissionlatency reduction may be particularly beneficial to Satellite based ISPcommunication systems).

A principal feature to determine the ultimate bandwidth savings of theembodiments is the selection of which data objects to store in theremote caches 332, 334, 336 as it is unrealistic to recreate the entirecontent of the Internet on each remote cache 332, 334, 336. At the ISP,a “listener” device/component/sub-system 304 listens to (i.e., monitors)the downstream replies 314 to see which data objects are being missed bythe remote caches 332, 334, 336. The listener 304 merely monitors thedownstream unicast reply (misses) traffic 314 without actively makingchanges in the downstream unicast reply (misses) traffic 314 beingdelivered to the ISP subscribers/clients 312. The harvester 306 records,analyzes and/or manipulates the downstream unicast reply (misses) 314and selects requested objects to multicast to the remote caches 332,334, 336 in order to improve the hit to miss ratio for replying torequests at the remote caches 332, 334, 336. The harvester 306 mayestimate the bandwidth utilized to transmit the unicast reply (misses)314 on the downstream portion of the ISP communication system 308 basedon the monitored downstream unicast replies (misses) 314 and, in turn,calculate the available downstream bandwidth available for multicastingdata objects to the remotes caches 332, 334, 336 as a difference betweenthe maximum total downstream bandwidth available for the ISPcommunication system 308 and the estimated unicast bandwidth being usedby the downstream unicast reply traffic 314. The harvester 306 may thenprioritize the data objects to deliver to the remote caches 332, 334,336 via multicast message 316 transported using the free/unused portionof the ISP communication system downstream bandwidth 308. Factors thatmay be used to prioritize the data objects to multicast 316 to theremote caches 332, 334, 336 may include, but is not limited to, thedelivery cost/size of the object (typically measured in kB—kilo bytes),the Time To Live (TTL)/expiry time for an object (typically measured inseconds), the frequency that the object is being requested (typicallymeasured in requests/second), the number of remote caches connected tothe ISP communication system 308, the total maximum downstream bandwidthmeasured/observed for the ISP communication system 308, and thefree/unused bandwidth available to multicast 316 objects to the remotecaches 332, 334, 336. Various embodiments may monitor and adjust forvariations in the measurements to evaluate and prioritize the dataobjects in real time such that the remote caches 332, 334, 336distributed at various locations (i.e., distributed caches) areadaptively updated via multicast data 316 sent by the harvester 306containing the most recent and high priority data objects encountered bythe harvester 308.

FIG. 4 is detailed flow chart/schematic illustration 400 of theoperation of the harvester 404 in a distributed cache—adaptive multicastarchitecture. As also described in the disclosure with respect to FIG.3, the downstream unicast replies representing items missed in theremote caches 450 are sent from the Internet to all subscribers 452 viathe ISP communication system 406, with each individual unicast replyaddressed to a particular end user device/application. A listener 402 atthe ISP supplies a copy of the downstream unicast replies (misses) 450to the harvester 404. The harvester 404 captures/records, analyzes, andprioritizes the data objects contained in the downstream unicast replies(misses) 450. An embodiment may incorporate a number of subsystemswithin the harvester 404 as shown in FIG. 4. The downstream replybandwidth estimator 408 estimates the bandwidth 454 utilized to deliverthe downstream unicast replies (misses) 450. The estimated downstreamunicast reply bandwidth 454 is then used in the available multicastbandwidth estimator 410 to calculate the available multicast bandwidth442 as a difference between the estimated downstream unicast replybandwidth 454 and the total maximum downstream bandwidth/pipe size ofthe ISP communication system 406. Eq. 1 represents a basic differencecalculation that may be used to calculate the available downstreammulticast bandwidth 442.Avail Multicast BW=Pipe Size−Estimated Downstream Unicast BW  Eq. 1:

Adjustments to the estimated downstream unicast bandwidth 454 may beperformed in real time such that the estimated downstream unicastbandwidth 454 and the available downstream multicast bandwidth 442 areupdated on a regular basis during system operation in order to permitthe harvester 404 to adjust for real time fluctuations in the bandwidthvalues. Various embodiments may utilize a fixed “theoretical” value ofthe maximum total downstream bandwidth of the ISP communication system406 that is based on the system parameters of the ISP communicationsystem 406. However, the actual currently available total maximumdownstream bandwidth of the ISP communication system 406 may fluctuatein real time due to a variety of real world factors that may fluctuateand/or may be difficult to properly incorporate into the calculation ofa theoretical total maximum downstream bandwidth value. For a satellitebased ISP communication system, fluctuations in the total maximumbandwidth currently available may include: weather effects on thesatellite signal, temperature effects on the satellite signal,temperature effects on the equipment, loss/addition of communicationchannels to the system, loss/addition of remote locations to the system,signal attenuation at the transceivers, etc.

The harvester 404 also creates a pool of cacheable objects 440 from therequested objects being delivered in the downstream unicast replies(misses) 450 monitored by the listener 402. Prior to placing a requestedobject into the pool of cacheable objects 440, the harvester 404 mayreject/exclude objects that should not be multicasted 446 to the remotecaches 448. For instance, an object may be designated as cacheable ornon-cacheable in the object parameters, an object may have a TTL/expirytime that is too short for reasonable and/or efficient use at the remotecaches (i.e., the object will expire before or soon after the multicastdata 446 is sent to and handled by the remote caches 448), or the objectmay contain objectionable material from a forbidden domain. Theharvester may inspect the objects in the downstream unicast replies(misses) 450 to determine if the object is cacheable 412. If the objectis not cacheable 414, the object is ignored 416 and not included in thepool of cacheable objects 440. If the object is cacheable 418 andotherwise acceptable, the object may be included in the pool ofcacheable objects 440. The harvester may also inspect each object'sTTL/expiry time 450 to determine if the object will be valid long enoughthat multicasting 446 the object to the remote caches 448 may reasonablyprovide some bandwidth savings 420. For instance, if the TTL/expiry timeis one second and it takes 1-2 seconds to multicast the object to theremote caches 448, then, by the time the object arrives at the remotecaches, the object has expired and is useless to the remote cache. Ifthe TTL/expiry time is too short, the object is ignored 424 and notincluded in the pool of cacheable objects 440. Further, a function ofthe combination of the TTL/expiry time and the content size (i.e.,delivery cost) may be used to prioritize objects to multicast. Forinstance, a large object with a relatively short TTL/expiry time maystill be worth caching while a small object with the same TTL/expirytime may not be worth caching. If the object has a sufficiently longTTL/expiry time 426 and is otherwise acceptable, the object may beincluded in the pool of cacheable objects 440. Further, the harvestermay inspect the content of each object to determine if the objectoriginated from a forbidden domain 428. Similar functionality may beachieved by the harvester 404 using a content filter (e.g., Net Nannyand the like) to actively inspect the data for unwanted content 428. Insome circumstances, objectionable material is some of the mostfrequently requested material on the Internet. If an ISP does not wantto deliver objectionable material to remote caches, it may be worthwhileto exclude objects with objectionable material from the pool ofcacheable objects 440. Excluding objectionable material may obviate therisk of the ISP from delivering illegal objectionable content to theremote caches and/or delivering content to a subscriber/client that theclient would find objectionable. If the object originated from aforbidden domain and/or an active content filter determined the contentis forbidden 430, the object is ignored 430 and not included in the poolof cacheable objects 440. If the object is not objected to for content434 and is otherwise acceptable, the object may be included in the poolof cacheable objects 440. Various embodiments may include parametersdefining minimum content/delivery cost size, maximum content/deliverycost size, and a minimum TTL/expiry time for objects that may bemulticasted to the remote caches 332, 334, 336. Various embodiments mayalso permit the user to define that only objects requested by aparticular user/remote location may be stored in the remote cache 332,334, 336 for the particular remote location. That is, the multicastedobjects to cache may contain objects commonly accessed by otherusers/remote locations, but that are not used or desired to be cached bythe particular user/remote location 33

The prioritizer 436 may then prioritize each object in the pool ofcacheable objects 440 based on a calculated measure of the bandwidthsavings provided by remotely caching the object. As further described inthe disclosure with respect to FIG. 6, the prioritizer 436 may determinethe bandwidth savings for each object as a function of the deliverycost/size of the object (typically measured in kB—kilo bytes), the TimeTo Live (TTL)/expiry time for an object (typically measured in seconds),and the frequency that the object is being requested (typically measuredin requests/second). In addition to the above, the prioritizer maycalculate the bandwidth savings for each object as a function of thenumber of remote caches connected to the ISP communication system and/orthe total maximum downstream bandwidth measured/observed for the ISPcommunication system 406. Once the pool of cacheable objects 440 isprioritized, the available multicast bandwidth 442 determines how manydata objects may be sent downstream in the available multicast bandwidth442. The pool of cacheable objects 440 is added to the multicast queue444 from highest priority to lowest priority objects based on eachobject's bandwidth savings until the multicast queue is full, asdetermined by the available multicast bandwidth 442. The estimateddownstream unicast reply bandwidth 454, available multicast bandwidth442, measured/observed total maximum downstream bandwidth of the ISPcommunication system 406, and the individual priorities of the objectsin the pool of cacheable objects may be updated during system operationin real time such that the remotely cached items are continuouslyadapted to the actual subscriber/client usage patterns. An embodimentmay perform the priority calculation to obtain an object's priorityvalue using a simple equation, such as the equation given in Eq. 2below.

$\begin{matrix}{{Objectpriority} = \frac{( {{Size}*{Scalar}\; 1} )*( {{Frequency}*{Scalar}\; 2} )*( {{TTL}*{Scalar}\; 3} )}{{Scalar}\; 4}} & {{Eq}.\mspace{14mu} 2}\end{matrix}$The scalar 1-4 factors in Eq. 2 represent constant parameters that maybe set by the ISP to meet the ISP's prioritization goals. For anembodiment implementing Eq. 2, the embodiment may also set a minimumand/or maximum for each parameter (e.g., restrict objects within amaximum and/or minimum range for delivery cost/size, frequency/requestsper second, and/or the TTL/expiry time). Other relationships between theparameters may also be utilized as desired to set the priority valuesfor each object. Also, other parameters may be incorporated into apriority function, such as the number of remote caches on the systemand/or the currently available maximum ISP system communicationbandwidth.

FIG. 5 is a flow chart 500 describing the operation of an embodimentthat maximizes use of available bandwidth on an ISP to ISPsubscriber/client communication system. At step 502, the embodimentlistens to (i.e., monitors) the downstream traffic on the ISPcommunication system. At step 504, the embodiment estimates thedownstream unicast reply bandwidth based on the downstream unicasttraffic listened to (i.e., monitored) in step 502 and the maximum totaldownstream bandwidth of the ISP communication system. At step 506, theembodiment places the requested objects contained in the downstreamunicast replies of the downstream unicast traffic into a pool ofcacheable objects. At step 508, the embodiment determines the availabledownstream multicast bandwidth based on the difference between themaximum total downstream bandwidth of the ISP communication system andthe estimated unicast reply bandwidth from step 504. At step 510, theembodiment determines a bandwidth (BW) savings for each requested objectin the pool of cacheable objects as a function of the delivery cost/sizeof each object (typically measured in kB—kilo bytes), the Time To Live(TTL)/expiry time for each object (typically measured in seconds), andthe frequency that the object is being requested (typically measured inrequests/second). In addition to the above, the embodiment may calculatethe bandwidth savings for each object in the pool of cacheable objectsas a function of the number of remote caches connected to the ISPcommunication system and/or the total maximum downstream bandwidthmeasured/observed for the ISP communication system. At step 512, theembodiment prioritizes the objects in the pool of cacheable objectsbased on the bandwidth savings for each object determined in step 510.At step 514, the embodiment determines a sub-group of objects in thepool of cacheable objects to place in a queue of cacheable objects tomulticast to the remote caches as a function of the prioritized pool ofcacheable objects and the available downstream multicast bandwidth. Inother words, the queue of cacheable objects is filled from the highestpriority objects to the lowest priority objects in the prioritizedcacheable object pool of step 512 until it is determined that the queueof cacheable objects will fill the available downstream multicastbandwidth as determined at step 508. At step 516, the embodimentdelivers the objects in the queue of cacheable objects to the remotescaches using multicast transmission technology. At step 518, theembodiment saves bandwidth usage on the ISP communication system byhaving the remote cache intercept and respond to requests for objectsthat are contained in the remote cache without forwarding or otherwiseaccessing the ISP communication system to handle the intercepted requestfor the objects found (hits) in the remote cache.

FIG. 6 is a flow chart 600 describing operation of the prioritizer toprioritize objects in the pool of cacheable objects. At step 602, theprioritizer adjusts the bandwidth savings for each object in the pool ofcacheable objects as a function of the delivery cost/size of the object(typically measured in kB). At step 604, the prioritizer adjusts thebandwidth savings for each object in the pool of cacheable objects as afunction of the Time To Live (TTL)/expiry time of the object (typicallymeasured in seconds). At step 606, the prioritizer adjusts the bandwidthsavings for each object in the pool of cacheable objects as a functionof the frequency that the object is requested (typically measured inrequests/second). At optional step 608, the prioritizer adjusts thebandwidth savings for each object in the pool of cacheable objects as afunction of the number of remote caches connected to the ISPcommunication system. At optional step 610, the prioritizer adjusts thebandwidth savings for each object in the pool of cacheable objects as afunction of the currently available maximum total downstream bandwidth(typically measured in kbps or Mbps). At step 612, the prioritizerprioritizes the objects in the pool of cacheable objects based on thedetermined bandwidth savings for each object.

FIG. 7 is a flow chart 700 describing operation of an embodiment tooverwrite or create Time To Live (TTL)/expiry times for objects in themulticast queue. At step 702, the embodiment described in the flow chart700 of FIG. 7 examines the TTL/expiry time for each object in the queueof objects to multicast to the remote caches in order to determine ifthe TTL/expiry time is indeterminate. Some potential indeterminateTTL/expiry times include objects without any TTL/expiry time defined(i.e., no TTL/expiry time), objects with an infinite TTL/expiry time,and objects that have some otherwise indeterminate TTL/expiry time. Atstep 704, the embodiment overwrites/creates the TTL expiry time of theobject with an indeterminate TTL/expiry time with a TTL/expiry timedesigned to maximize the bandwidth saving effectiveness of the systemwhile maintaining a reasonable ability to keep the objects stored in theremote caches up-to-date with any changes that may be made to the objecton the originating Internet source. Many format construction objectssuch as lines, counters, backgrounds, etc. have been found to haveindeterminate TTL/expiry times. The format construction objects wereoften not cached because the TTL/expiry time indicated that the objectneed be refreshed each time a web page was accessed. By updating theTTL/expiry time to a measureable TTL/expiry time for objects withindeterminate TTL/expiry times, it was found that the formatconstruction type objects could be effectively cached at the remotecache. Thus, with the indeterminate TTL/expiry time objects cached,bandwidth needed to download objects that rarely change is saved.Further, for systems where transmission latency is an issue (e.g.,satellite), the remote cache is able to intercept the repeated accessesto the same object and save significant time due to latency concerns.Further, many times a web site will repeatedly check the TTL/expiry timefor objects with indeterminate TTL/expiry times and providing adeterminable TTL/expiry time eliminates much of the need to continuallycheck for an update of the TTL/expiry times.

The various embodiments may also combine a predefined list of knownobjects with the actively adapted object queue provided for multicastingto the remote queues by the harvester. A predefined list may provide theability to regularly keep a list of objects known to be popular even ifthere may be a real time lull in the access of the objects on the list.Further, the predefined list may provide an additional ability for ISPsubscriber/clients to define a list of objects the subscriber/clientdesires to be cached.

Various embodiments may provide the control and management functionsdetailed herein via an application operating on a computer system (orother electronic devices). Embodiments may be provided as a computerprogram product which may include a computer-readable, ormachine-readable, medium having stored thereon instructions which may beused to program/operate a computer (or other electronic devices) orcomputer system to perform a process or processes in accordance with thepresent invention. The computer-readable medium may include, but is notlimited to, hard disk drives, floppy diskettes, optical disks, CompactDisc Read-Only Memories (CD-ROMs), Digital Versatile Disc ROMS(DVD-ROMs), Universal Serial Bus (USB) memory sticks, magneto-opticaldisks, ROMs, random access memories (RAMs), Erasable Programmable ROMs(EPROMs), Electrically Erasable Programmable ROMs (EEPROMs), magneticoptical cards, flash memory, or other types of media/machine-readablemedium suitable for storing electronic instructions. The computerprogram instructions may reside and operate on a singlecomputer/electronic device or various portions may be spread overmultiple computers/devices that comprise a computer system. Moreover,embodiments may also be downloaded as a computer program product,wherein the program may be transferred from a remote computer to arequesting computer by way of data signals embodied in a carrier wave orother propagation medium via a communication link (e.g., a modem ornetwork connection, including both wired/cabled and wirelessconnections).

The foregoing description of the invention has been presented forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention to the precise form disclosed, andother modifications and variations may be possible in light of the aboveteachings. The embodiment was chosen and described in order to bestexplain the principles of the invention and its practical application tothereby enable others skilled in the art to best utilize the inventionin various embodiments and various modifications as are suited to theparticular use contemplated. It is intended that the appended claims beconstrued to include other alternative embodiments of the inventionexcept insofar as limited by the prior art.

What is claimed is:
 1. A computerized method for maximizing use ofcommunication bandwidth on an ISP communication system connecting atleast one remote location to an Internet Service Provider (ISP), saidISP communication system having a maximum total downstream bandwidthavailable to transmit objects downstream from said ISP to said at leastone remote location, said at least one remote location having a remotecache, said computerized method comprising: determining a bandwidthsavings from remote caching for each requested object in a pool ofcacheable objects as a function of a delivery cost/size of eachrequested object, a Time To Live (TTL)/expiry time of each requestedobject, and a frequency of request for each requested object, said poolof cacheable objects being requested objects contained in downstreamunicast replies of downstream unicast communication traffic of said ISPcommunication system; prioritizing said requested objects in said poolof cacheable objects based on said determined bandwidth savings for eachrequested object in said pool of cacheable objects; determining asub-group of said requested objects in said pool of cacheable objects toplace in a queue of multicast cacheable objects to multicast to saidremote cache at said at least one remote location based on saidprioritized pool of cacheable objects and an available downstreammulticast bandwidth; delivering objects in said queue of multicastcacheable objects to said remote cache at said at least one remotelocation via multicast transmissions downstream from said ISP to saidremote location; intercepting requests sent upstream from said at leastone remote location for objects contained in said remote cache at saidremote cache; and responding to said intercepted requests by said remotecache at said at least one remote location with replies containing saidrequested objects contained in said remote cache such that upstream anddownstream bandwidth on said ISP communication system is saved byexcluding upstream requests for, and downstream replies containing, saidrequested objects contained in said remote cache.
 2. The computerizedmethod of claim 1 wherein said determining of said bandwidth savingsfrom remote caching for each requested object in said pool of cacheableobjects is further a function of a number of remote caches connected tosaid ISP communication system, said number of remote caches indicating anumber of remote locations with said remote cache connected to said ISPcommunication system.
 3. The computerized method of claim 1 wherein saiddetermining of said bandwidth savings from remote caching for eachrequested object in said pool of cacheable objects is further a functionof said maximum total downstream bandwidth currently available to saidISP communication system.
 4. The computerized method of claim 1 whereinsaid pool of cacheable objects excludes objects designated as not beingcacheable.
 5. The computerized method of claim 1 wherein said pool ofcacheable objects excludes objects with a Time To Live (TTL)/expiry timedetermined to be too short to deliver to said remote cache at said atleast one remote location.
 6. The computerized method of claim 1 whereinsaid pool of cacheable objects excludes objects originating from adomain forbidden to be cached.
 7. The computerized method of claim 1wherein said pool of cacheable objects excludes objects designated asundesirable by a content control filter actively monitoring saidrequested objects monitored in said downstream unicast communicationtraffic.
 8. The computerized method of claim 1 further comprisingcombining a predefined list of objects with said requested objectsmonitored in said downstream unicast communication traffic in said poolof cacheable objects.
 9. The computerized method of claim 1 furthercomprising: examining said Time To Live (TTL)/expiry time of eachrequested object in said queue of multicast cacheable objects todetermine if said Time To Live (TTL)/expiry time of each requestedobject in said queue of multicast cacheable objects is indeterminate;and overwriting/creating said Time To Live (TTL)/expiry time in arequested object contained in said queue of multicast cacheable objectswith a pre-defined replacement expiry time if said Time To Live(TTL)/expiry time of said requested object contained in said queue ofmulticast cacheable objects is found to have no expiration, negativeexpiration, or some otherwise indeterminable expiration.
 10. Thecomputerized method of claim 1 wherein said ISP communication systemconnects to at least one additional remote location that does not have aremote cache.
 11. The computerized method of claim 1 wherein said atleast one remote location restricts storage of objects in said remotecache of said at least one remote location to objects requested by saidat least one remote location and not other remote locations.
 12. Adistributed cache adaptive multicast system for maximizing use ofcommunication bandwidth on an ISP communication system connecting atleast one remote location to an Internet Service Provider (ISP), saidISP communication system having a maximum total downstream bandwidthavailable to transmit objects downstream from said ISP to said at leastone remote location, said at least one remote location having a remotecache, said distributed cache adaptive multicast system comprising: aprioritizer subsystem that determines a bandwidth savings from remotecaching for each requested object in said pool of cacheable objects as afunction of a delivery cost/size of each requested object, a Time ToLive (TTL)/expiry time of each requested object, and a frequency ofrequest for each requested object, said pool of cacheable objects beingrequested objects contained in downstream unicast replies of downstreamunicast communication traffic of said ISP communication system, and thatprioritizes said requested objects in said pool of cacheable objectsbased on said determined bandwidth savings for each requested object insaid pool of cacheable objects; a multicast queue subsystem thatdetermines a sub-group of said requested objects in said pool ofcacheable objects to place in a queue of multicast cacheable objects tomulticast to said remote cache at said at least one remote locationbased on said prioritized pool of cacheable objects and said availabledownstream multicast bandwidth; and a multicast delivery subsystem thatdelivers objects in said queue of multicast cacheable objects to saidremote cache at said at least one remote location via multicasttransmissions downstream from said ISP to said remote location in orderto permit said at least one remote cache to intercept requests sentupstream from said at least one remote location for objects contained insaid remote cache at said remote cache, and to respond to saidintercepted requests by said remote cache at said at least one remotelocation with replies containing said requested objects contained insaid remote cache such that upstream and downstream bandwidth on saidISP communication system is saved by excluding upstream requests for anddownstream replies containing said requested objects contained in saidremote cache.
 13. The distributed cache adaptive multicast system ofclaim 12 wherein said prioritizer subsystem further determines saidbandwidth savings from remote caching for each requested object in saidpool of cacheable objects as a function of a number of remote cachesconnected to said ISP communication system, said number of remote cachesindicating a number of remote locations with said remote cache connectedto said ISP communication system.
 14. The distributed cache adaptivemulticast system of claim 12 wherein said prioritizer subsystem furtherdetermines said bandwidth savings from remote caching for each requestedobject in said pool of cacheable objects as a function of said maximumtotal downstream bandwidth currently available to said ISP communicationsystem.
 15. The distributed cache adaptive multicast system of claim 12wherein said pool of cacheable objects excludes objects designated asnot being cacheable.
 16. The distributed cache adaptive multicast systemof claim 12 wherein said pool of cacheable objects excludes objects witha Time To Live (TTL)/expiry time determined to be too short to deliverto said remote cache at said at least one remote location.
 17. Thedistributed cache adaptive multicast system of claim 12 wherein saidpool of cacheable objects excludes objects originating from a domainforbidden to be cached.
 18. The distributed cache adaptive multicastsystem of claim 12 wherein said pool of cacheable objects excludesobjects designated as undesirable by a content control filter activelymonitoring said requested objects monitored in said downstream unicastcommunication traffic.
 19. The distributed cache adaptive multicastsystem of claim 12 further comprising a predefined list subsystem thatcombines a predefined list of objects with said requested objectsmonitored in said downstream unicast communication traffic in said poolof cacheable objects.
 20. The distributed cache adaptive multicastsystem of claim 12 further comprising: an expiry update subsystem thatexamines said Time To Live (TTL)/expiry time of each requested object insaid queue of multicast cacheable objects to determine if said Time ToLive (TTL)/expiry time of each requested object in said queue ofmulticast cacheable objects is indeterminate, and overwrites/createssaid Time To Live (TTL)/expiry time in a requested object contained insaid queue of multicast cacheable objects with a pre-defined replacementexpiry time if said Time To Live (TTL)/expiry time of said requestedobject contained in said queue of multicast cacheable objects is foundto have no expiration, negative expiration, or some otherwiseindeterminable expiration.
 21. The distributed cache adaptive multicastsystem of claim 12 wherein said ISP communication system connects to atleast one additional remote location that does not have a remote cache.22. The distributed cache adaptive multicast system of claim 12 whereinsaid at least one remote location restricts storage of objects in saidremote cache of said at least one remote location to objects requestedby said at least one remote location and not other remote locations. 23.A distributed cache adaptive multicast system for maximizing use ofcommunication bandwidth on an ISP communication system connecting atleast one remote location to an Internet Service Provider (ISP), saidISP communication system having a maximum total downstream bandwidthavailable to transmit objects downstream from said ISP to said at leastone remote location, said at least one remote location having a remotecache, said distributed cache adaptive multicast system comprising:means for determining a bandwidth savings from remote caching for eachrequested object in said pool of cacheable objects as a function of adelivery cost/size of each requested object, a Time To Live (TTL)/expirytime of each requested object, and a frequency of request for eachrequested object, said pool of cacheable objects being requested objectscontained in downstream unicast replies of downstream unicastcommunication traffic of said ISP communication system; means forprioritizing said requested objects in said pool of cacheable objectsbased on said determined bandwidth savings for each requested object insaid pool of cacheable objects; means for determining a sub-group ofsaid requested objects in said pool of cacheable objects to place in aqueue of multicast cacheable objects to multicast to said remote cacheat said at least one remote location based on said prioritized pool ofcacheable objects and said available downstream multicast bandwidth;means for delivering objects in said queue of multicast cacheableobjects to said remote cache at said at least one remote location viamulticast transmissions downstream from said ISP to said remotelocation; means for intercepting requests sent upstream from said atleast one remote location for objects contained in said remote cache atsaid remote cache; and means for responding to said intercepted requestsby said remote cache at said at least one remote location with repliescontaining said requested objects contained in said remote cache suchthat upstream and downstream bandwidth on said ISP communication systemis saved by excluding upstream requests for, and downstream repliescontaining, said requested objects contained in said remote cache.